Synergistic compositions for the control of aerobacter aerogenes

ABSTRACT

The present invention relates to certain processes and compositions useful for inhibiting and/or controlling the growth of slime in water and, in particular, water employed for industrial purposes. Water employed in the manufacture of pulp paper and water employed in cooling water systems, as well as other industrial waters, provide environments which are conducive to slime formation. The novel compositions of the present invention are mixtures which show unexpected synergistic activity against microorganisms, including bacteria, fungi and algae, which produce slime in aqueous systems. The slime, of course, is objectionable from an operational and/or an aesthetic point of view. Specifically, the invention is directed to and the use of compositions comprising a combination of 5-chloro-4-phenyl-1,2dithiole-3-one and phenolic compounds (or mixtures thereof). The inventive compositions inhibit the growth of slime in water, or more specifically, possess biocidal activity against bacteria, fungi and/or algae. The phenolic compounds contemplated for use in accordance with the present invention are those phenolic compounds which possess the capacity to kill or inhibit the growth of slime-forming microorganisms such as bacteria, fungi and algae. The type phenolic compounds encompassed by the present invention may be exemplified by: phenol, ortho-phenylphenol, 2, 3, 4, 6-tetrachlorophenol, 4-chloro-2-cyclopentylphenol and 2chloro-4-phenylphenol.

United States Patent [1 1 Brink, Jr, et a1.

[ 1 Mar. 25, 1975 1 SYNERGHSTIC COMPOSITIONS FOR THE CONTROL OF AEROBACTER AEROGENES [75] Inventors: Robert H. Brink, Jr., Doylestown;

Bernard F. Shema, Glenside; Roger L. Justice, Cornwells Heights; Paul Swered, Philadelphia, all of Pa.

[73] Assignee: Betz Laboratories, Inc., Trevose, Pa.

[22] Filed: Apr. 4, 1974 [21] Appl. No.: 457,744

Related U.S. Application Data [62] Division of Ser. No. 160,191, July 6, 1971, Pat. No.

[51] Int. Cl A01n 9/02 [58] Field oi Search 7l/67, 424/347, 277, 346

[56] References Cited UNITED STATES PATENTS 2,997,380 8/1961 Josephs 71/66 1031372 4/1962 Brock 424/277 3,824,318 7/1974 Shema et all t 71/67 3,829,305 8/1974 Brink, Jr. et a1 71/67 Primary Examiner-James 0. Thomas, Jr. Attorney, Agent, or Firm-Alexander D. Ricci [57] ABSTRACT The present invention relates to certain processes and compositions useful for inhibiting and/or Controlling the growth of slime in water and, in particular, water employed for industrial purposes. Water employed in the manufacture of pulp paper and water employed in cooling water systems, as well as other industrial waters, provide environments which are conducive to slime formation. The novel compositions of the present invention are mixtures which show unexpected synergistic activity against microorganisms, including bacteria, fungi and algae, which produce slime in aqueous systems. The slime, of course, is objectionable from an operational and/or an aesthetic point of 1 view. Specifically, the invention is directed to and the use of compositions comprising a combination of 5- chloro-4phenyl-1,2-dithiole-3-one and phenolic compounds (or mixtures thereof). The inventive compositions inhibit the growth of slime in water, or more spe' cifically, possess biocidal activity against bacteria, fungi and/or algae. The phenolic compounds contemplated for use in accordance with the present invention are those phenolic compounds which possess the capacity to kill or inhibit the growth of slime'forming microorganisms such as bacteria, fungi and algae. The type phenolic compounds encompassed by the present invention may be exemplified by: phenol. ortho phenylphenol, 2, 3, 4, 6-tetrachlorophenol, 4-chloro- Z-cyclopentylphenol and 2-chloro-4-phenylphenol.

3 Claims, N0 Drawings SYNERGISTIC COMPOSITIONS FOR THE CONTROL OF AEROBACTER AEROGENES This is a division of application Ser. No. 160,191 filed July 6, 1971, now US. Pat. No. 3,829,305.

BACKGROUND OF THE INVENTION The formation of slime by microorganisms is a problem which attends many systems. For example, lagoons, lakes, ponds, pools and such systems as cooling water systems and pulp and paper mill systems all possess conditions which are conducive to the growth and reproduction of slime-forming microorganisms. In both once-through and recirculating cooling systems, for example, which employ large quantities of water as a cooling medium, the formation of slime by microorganisms is an extensive and constant problem.

Airborne organisms are readily entrained in the water from cooling towers and find this warm medium an ideal environment for growth and multiplication. Aerobic and heliotropic organisms flourish on the tower proper while other organisms colonize and grow in such areas as the tower sump and the piping, and passages of the cooling system. Such slime serves to deteriorate the tower structure in the case of wooden towers. In addition, the deposition of slime on metal surfaces promotes corrosion. Futhermore, slime carried through the cooling system plugs and fouls lines, valves, strainers, etc. and deposits on heat exchange surfaces. In the latter case, the impedance of heat transfer can greatly reduce the efficiency of the cooling system.

In pulp and paper mill systems, slime formed by microorganisms is also frequently and, in fact, commonly encountered. Fouling or plugging by slime also occurs in the case of pulp and paper mill systems. Of greater significance, the slime becomes entrained in the paper produced to cause breakouts on the paper machines with consequent work stoppages and the loss of production time or unsightly blemishes in the final product; this, of course, results in rejects and wasted output. The previously discussed problems have resulted in the extensive utilization of biocides in cooling water and pulp and paper mill systems. Materials which have enjoyed widespread use in such applications include chlorine, organo-mercurials, chlorinated phenols, organobromines, and various organo-sulfur compounds. All of these compounds are generally useful for this purpose but each is attended by a variety of impediments. For example, chlorination is limited both by its specific toxicity for slime-forming organisms at economic levels and by the ability of chlorine to react which results in the expenditure of the chlorine before its full biocidal function may be achieved. Other biocides are attended by high costs, odor problems and hazards in respect to storage, use or handling which limit their utility. To date, no one compound of type of compound has achieved a clearly established predominance in respect to the applications discussed. Likewise, lagoons, ponds, lakes and even pools, either used for pleasure purposes or used for industrial purposes for the disposal and storage of industrial wastes become, during the warm weather, besieged by slime due to microorganism growth and reproduction. In the case of the recreational areas, the problem of infection, odor, etc., is obvious. In the case of industrial storage or disposal of industrial materials, the microorganisms cause additional problems which must be eliminated prior to the materials use or the waste is treated for disposal.

It is the object of the present invention to provide compositions for controlling slime-forming microorganisms in aqueous systems, such as cooling water systems and pulp and paper mill systems, and for controlling slime formation or microorganism populations in aqueous bodies in general. Moreover, another object of the invention is the provision of methods for preserving materials and for controlling slime-forming microorganisms in any aqueous system which is conducive to the growth and reproduction of microorganisms and, in particular, cooling water and paper and pulp mill systems. These methods employ a combination of 5 chloro-4-phenyl-1,2-dithiole-3-one and a phenolic compound (or mixtures thereof). The phenolic compound must possess the property of being biocidally active against bacteria, fungi and/or algae, i.e., either kill or inhibit the growth of these microorganisms.

In the practice of the invention, the combination is added to the particular material to be preserved or to the system being treated, for example cooling water systems, paper and pulp mill systems, pools, ponds, lagoons, lakes, etc., in a quantity adequate to control the slime-forming microorganisms which are contained by, or which may become entrained in, the system which is treated. It has been found that such compositions and methods control the growth and occurrence of such microorganisms as may populate these particular systems.

GENERAL DESCRIPTION OF THE INVENTION As earlier stated, the inventive compositions comprise a combination of 5-chloro-4-phenyl-l,Z-dithiole- 3l-one and a particular phenolic compound (or mixtures thereof) with either compound being present in such a quantity as to impart a synergistic behavior for the purpose to the composition as a whole. Preferably, the compositions contain a percentage by weight ranging from about 5 to about of the dithiole-3-one compound and from about 5 to about 95% of the phenolic compound. When these two ingredients are mixed either beforehand or by addition to the aqueous system individually, the resulting mixtures possess a high degree of slimicidal activity which could not have been predicted beforehand from the known activity of the individual ingredients comprising the mixture. Accordingly, it is therefore possible to produce a more effective slime-control agent than has previously been available. Because of the enhanced activity of the mixture, the total quantity of biocide required for an effective treatment may be reduced. In addition, the high degree of biocidal effectiveness which is provided by each of the ingredients may be exploited without use of the higher concentrations of each. This feature is not only important and advantageous from an economical point of view, but also most desirable from the pollution or ecological standpoints. In this regard, it might be pointed out that the smaller the amount of a chemical that is required for effective treatment, the smaller the problem in treating the wastes from these systems. In both cooling water systems and in paper and pulp mill systems, certain discharge of waste water, e.g., blowdown in cooling water systems, is a necessity. However, because of the current concern and legislation regarding the discharge of wastes, the effluent waste water must be treated to reduce and, hopefully, to eliminate any undesirable constituents. This treatment, of course, is time consuming and costly. Accordingly, a reduction in additive usage will result in a corresponding reduction in costs for the treatment of wastes containing these additives.

To demonstrate the synergism which is obtainable from the combination of the phenolic compounds with the 5-chloro-4-phenyl-l,2-dithiole-3-one (supplied by Hercules Corporation under designation 8-1 612), various exemplary phenolic compounds were chosen. As earlier indicated, synergistic activity can be obtained by combining the dithiole-3-one compound with phenolic compounds" which exhibit growth inhibitory or biocidal activity with respect to bacteria, fungi and/or algae. The phenolic compounds which were chosen as representative are as follows: phenol, orthophenylphenol (Dow Chemical Company Dowicide l); 2-chloro-4-phenylphenol (Dowicide 4); 2, 3, 4, 6- tetrachlorophenol (Dowicide 6); and 4-chloro-2- cyclopentylphenol.

In order to illustrate the synergistic activity, the efficacy and the comparative effectiveness of the inventive 4 Microbiology, 9, 53841, (1961)] and the relationships,

QA/Qn 05/ Oh l is additivity 1 is antagonism l is synergism where,

TABLE 1 Weight Ratio Quantities Producing End Points (ppm) Q /Q of A to B 0,, Q Mixture Q /QH Qn/Qb QB/Qb compositions, various tests were utilized and will be described following.

SPECIFIC EMBODIMENTS EXAMPLE 1 SYNERGISTIC COMBINATION:

Compound A: 5-chloro-4-phenyl-l,2-dithiole- 3-one Compound B: Phenol The compositions of this Example contained 5-chloro-4-phenyl-l ,2 .dithiole-3-one (referred to as Compound A in the Test Equations and in Tables 1 through 1C) and phenol (referred to as Compound B in this Example and in the Test Equations and in Tables 1 through 1C) in the weight ratios expressed in the Tables which follow. The compositions were tested for synergistic activity in accordance with the method described. The synergism test was utilized to evaluate each of the combinations of this Example and the following Examples.

Synergistic lndex Test Synergistic activity was demonstrated by adding Compound A and Compound B in varying ratios and over a range of concentrations to liquid nutrient medium which was subsequently inoculated with a standard volume of suspension of the bacterium Aerobacter 'aerogenes. Following two days incubation, the lowest concentration of each ratio which prevented growth of the bacteria was taken as the end point. Growth or no growth was determined by turbidity or clarity respectively in the medium. End points for the various mixtures were then compared with end points for the pure active ingredients working alone in concomitantly prepared culture bottles. Synergism was determined by the method described by Kull et a1 [F. C. Kull, P. C. Eisman, H. D. Sylwestrowicz and R. L. Mayer, Applied It is evident from the data recorded in Table 1 that compositions of the present invention function to control slime growth due to microorganisms not only at equal portions of the respective ingredients, but also where just minor amounts of one or the other are prescm. This discovery of synergism at the lower levels is extremely valuable since it illustrates conclusively that the ingredients are compatible over the wide percentage by weight range.

BACTERICIDAL EFFECTIVENESS The bactericidal effectiveness of the mixture of Compound A and Compound B of this Example is demonstrated by the following Table in which the inhibiting power of a 50/50 by weight mixture of A and B is shown. Aerobacter aerogenes was employed as the test organism and a substrate technique was utilized. Specifically, the biocidal mixture was added in gradually increasing quantities to nutrient agar media which was then inoculated with A. aerogenes. The preparation was then incubated for 48 hours. The values set forth in the Table indicate the quantity of biocide required, in parts by weight for each 1 million parts by weight of the medium, in order to achieve complete inhibition of the growth of the test organism.

TABLE 1A Quantity (ppm) required for inhibition Biocidal Material of A. aerogenes Compound A (5%), Compound B (5%), 300

Inert FUNGICIDAL EFFECTIVENESS ing the procedures described by B. F. Shema and J. H. Conkey [Journal for the Technical Association of The Pulp and Paper Industry, 36, A30A, (1953)]. The described procedure generally entails incorporating the biocide under test in a nutrient substrate such as agar, 5 some suitable time period(s) after beginning biocide malt, etc. and pouring the resulting medium into a Petri treatment ng h Counts in d from h pl ing. dish and allowing the medium to solidify. A button of the percentage kill (based on the initial control count) fungus inoculum is placed on the surface of the solidimay be calculated. In this evaluation the water sample ficd medium and the medium is incubated for a period was taken from a water tray ofa paper machine located of 14 days. After the period, the diameter ofthe colony 10 in the northeastern United States. is measured and compared with the diameter of the For the purposes of comparison, the mixture of A button of inoculum originally placed upon the surface. and B was evaluated together with two recognized If there is no increase in the diameter, the growth of the commercial biocides, Pentachlorophenol and a Comfungus is considered to be completely inhibited and the mercial Product.

TABLE lC Quantity of Percent kill Biocidal Material biocide (ppm) after 6 hours Compound A (5%), Compound B (5%), Inert (90%) 5 77 do. do. do. 10 89 do. do. do. 94 do. do. do. 50 99 do. do. 100 100 Pentachlorophenol (100%) 5 82 do. 10 91 do. 25 100 do. 50 100 do. I 100 100 Commercial Product active: Combination of dithiocarbamates) 5 72 do. 10 72 do. 25 73 do. 50 78 do. 100 88 treatment level which accomplished this is considered in inhibitory concentration. The fungal species utilized as the test microorganism to evaluate the efficacy of the present mixture were Penicillium expansum and As- Incrt (90%) SLIME CONTROL EFFECTIVENESS The inventive methods and compositions were also tested with respect to their performance in the control of slime formation in industrial systems. In this test an industrial recirculating water was obtained from a systcm which was currently experiencing problems in respect to the formation of slime by microorganisms. Such tests do not demonstrate the efficiency of the biocide employed with respect to specific species of microorganisms but instead supply a practical demonstration of the efficacy of the biocide tested in relation to those communities of microorganisms which have evidenced their ability to form slime in actual industrial systems.

In the testing of recirculating water samples, a substrate evaluation was employed. In such testing identi- A perusal of the recorded percentages clearly establishes that the composition of the present invention, although less concentrated with respect to active ingredi ents as compared to the two commercial products, gave excellent rates of kill even at low treatment levels. As earlier expressed, excellent performance of a biocidal composition at low treatment levels not only provides a most desirable cost performance index, but also provides most desirable advantages from the aspects of pollution abatement, waste treatment cost and the preservation of the ecological strain.

EXAMPLE 2 SYNERGISTIC COMBINATION:

Compound A: 5'-chloro-4-phenyl-l,2 -dithiole-3-one Compound B: Orthophenylphenol The compositions of this Example contained 5' chloro-4-phenyl-1,2-dithiole-3-one (referred to as Compound A in the Test Equations and in Tables 2 through 2C) and ortho-phenylphenol (referred to as Compound B in this Example). The compositions of this Example were tested in accordance with the test procedures outlined in Example 1. The data ascertained for the respective tests are recorded below under the commensurate Table.

Synergistic Index Test For mixtures of Compounds A and B, and for Compound A and Compound B acting alone, the following cal portions of water samples are treated with varying results were observed:

TABLE 2 Quantities Wei ht Ratio Producing End Points lfppm) QJ/Qn o AtoB 0, QB xt 0.1/0 QB/QO Qa/Qn BACTERICIDAL EFFECTIVENESS The bactericidal effectiveness of the combination of this Example was tested in accordance with the procedure outlined in Example 1. The values obtained are The composition was quite effective in controlling fungus growth when it is considered that is contained only 10% active material.

5 SLIME CONTROL EFFECTIVENESS The test procedure used was that explained in Example 1. For comparative purposes, two commercial products were tested together with the composition of this Example. The water sample in this test was taken 10 from the air-washer sump of an industrial plant located in the northeastern United States.

TABLE 2C Quantity of Percent kill Biocidal Material biocide (ppm) after 6 hours Compound A (5%), Compound B (5%), Inert (90%) 5 do. do. do. 10 12 do. do. do. 25 35 do. do. do. 50 95 do. do. do. 100 100 Pentachlorophenol (100%) 41 do. 59 do. 87 do. 50 100 do. 100 100 Commercial Product active See Table 1C) 5 0 do. 10 0 do. 25 0 do. 50 18 do. 100 28 recorded in Table 2A which follows: 30 The results obtained for the inventive composition were comparable to the pentachlorophenol at high TABLE 2A treatment dosage and were overall superior to the Commercial Product which has found widespread ac- Quantity (ppm) ceptance and use. Moreover, when the low concentrarequired for inhibition Biocidal Material of A. aerogenes Compound A 5% Compound B 5% 300 Inert (90% FUNGICIDAL EFFECTIVENESS The effectiveness of the composition of Example 2 was tested in accordance with the procedures set forth in Example 1. The results were:

TABLE 28 Quantity (ppm) for inhibition 35 tions of the active ingredients are considered, it is obvious that the inventive composition was quite active in kill percentage.

EXAMPLE 3 40 SYNERGISTIC COMBINATION:

Synergistic Index Test Biocidal Material P. expansum A. niger For mixtures of Compounds A and B, and for Com- ComPound A (5%) Cmnpound B (5%) 500 500 pound A and Compound B acting alone, the following Inert 55 results were observed:

TABLE 3 Quantities Wei ht Ratio Producing End PointshSFpm) QA/Qll o A to B A B ixture Q /Qn QB/Qb QB/Qh The results obtained for this particular combination established unequivocally that the two ingredients behave synergistically together.

BACTERICIDAL EFFECTIVENESS compared with commercially available products using samples of water derived from the sump of an airwasher of an industrial cooling water system located in the northeastern United States.

The test procedure as described in Example I was utilized. The results established that the composition was effective in controlling this strain of bacteria.

TABLE 3A Quantity (ppm) required for inhibition Biocidal Material of A. aerogenes Compound A (5%), Compound B (5%), 300

Inert (90%) FUNGICIDAL EFFECTIVENESS The fungicidal activity of the composition of this Example was tested in accordance with the procedure previously described. The results were:

Again, the slime control effectiveness of the instant composition even at only 3 hour contact times was superior to the commercial products at low treatment ranges and was significantly better overall as compared to the 30% active Commercial Product.

EXAMPLE 4 SYNERGISTIC COMBINATION Compound A: 5-chIoro-4-phenyl-l,2-dithiole-3one Compound B: 2,3,4,6-tetrachlorophenol Synergistic Index Test The synergistic activity of the combinations of 5- chloro-4-phenyl -l,2 dithioIe-3-one (referred to as Compound A) and 2,3,4,6-tetrachlorophenol (referred to in this Example as Compound B) was evaluated in accordance with the test described. The results were as follows:

For mixtures of Compounds A nd B, and for Compound A and Compound B acting alone, the following results were observed:

TABLE 4 Weight Ratio Quantities Producing End Points (ppm) Q /Q, of A to B Q 5 Mixture Q /Q, Q /Qb Q /Q Trial 1 160 0 18.0

/50 14.0 14.0 28.0 0.778 0.047. 0.83 5/95 4.0 76.0 80.0 0.222 0.253 0.47 0/I00 300 Trial (2) 100/0 5.0

TABLE 38 The combinations exhibited a Q /Q Q /Q of less Quantity (ppm) for inhibition Biocidal Material 'P. expansum A. niger Compound A (5%), Compound B (5%), 500 500 Inert (90%) than I which, of course, established that the individual ingredients operated in concert to produce a synergistic result.

BACTERICIDAL EFFECTIVENESS The efficacy of the compositions of this Example was tested in accordance with the procedure outlined earlier. The results of the test clearly established that the combination of the instant invention is effective even at low percentages of active ingredients.

TABLE 4A EXAMPLE 5 SYNERGISTIC COMBINATION m f y gv mg Compound A: 5-chloro-4-phenyl-1,2-dithiole-3-one Biocidal material {k gl 'j g 'g Compound B: 4-chloro-Lcyclopentylphenol Synergistic lndex Test m? ":g%$ P" 55%) 300 The synergistic activity of the combinations of 5- chloro-4-phenyl-l,2-dithiole-3-one (referred to as Compound A) and 4-chloro-2-cyclopentylphenol (re- 10 ferred to in this Example as Compound B) was evalu- FUNGICIDAL EFFECTIVENESS ated in accordance with the test described. The results The fungicidal activity of the composition of this Exwere as I O ample was tested in accordance with the procedure For mixtures of Compounds A and B, and for Compreviously described. The result of this evaluation was pound A and Compound B acting alone, the following as follows: 5 resultswere observed:

TABLE 5 Wei ht Ratio Quantities Producing End Points (ppm) 0,10,, o A to B Q Q5 Mixture QA/Qa QB/Qb Oil/Ob TABLE 4B H 7 V V All of the combinations tested exhibited a Q /Q A Q /Q of less than 1 which, of course, established that Quantity (ppm) for inhibition the llldlVldUZldl'lgI'BdlCl'ltS operated in concert to pro- Biocidal Material P. expansum A. niger 3O duce a synerglsuc result ColmpougtqA 5% Compound B 5% 100 500 BACTERICIDAL EFFECTIVENESS ert n D The efficacy of the compositions of this Example was tested inaccordance with the procedure outlined ear- 7 35 lier. The results of the test clearly established that the SLIME CONTROL EFFECTIVENESS I combination of the instant invention is effective even As in the previous Examples and in the manner set at low percentages of active ingredients. forth in the previous Examples, the slime control effec- TABLE 5A tiveness of the composition of the Example was tested. The outcome of this evaluation and the data derived 4O gf g z using the Commercial Products are set forth in the fol- Biocidal Material f A aemgene:

lowing Table. The water sample used in this test was obtained from the airwasher sump of a cooling tower. cmpound A B (5%) 300 Inert 0% locatedgnthe northeastern United States. (9

TABLE 4C Quantity of Percent kill Biocidal Material biocide (ppm) after 6 hours Compound A (5%), Compound B (5%), lnert (90%) 5 35 do. do. do. 10 45 do. do. do. 64 do. do. do. 50 85 do. do. do. 100 100 Pentachlorophenol (100%) v 5 41 do. 10 59 do. 25 87 do. 50 100 do. 100 100 Commercial Product active See Table 1C) 5 0 do. 10 0 do. 25 0 do. 18 do. 100 28 The composition of this Example, as with the previ- FUNGICIDAL EFFECTIVENESS ous Examples, exhibited overall desirable and attracfive Slime control p yof Special interest in the The fungicidal activity of the composition of this Exfact that at low percentage active concentrations the ample was tested i accordance with the procedure COmPOSit OHS were apa of n r li g the Slimepreviously described. The result of this evaluation was forming organisms. V g as follows:

TABLE 58 Quantity (ppm) for inhibition Biocidal Material P. expansum A. niger Compound A Compound B (5%),

Inert (90%) SLIME CONTROL EFFECTIVENESS tained when the concentration or treatment level of the combination or admixture of biocides is between 0.5 parts per million to 1,000 parts per million, and preferably between I and 100 parts per million, based upon the total content of the aqueous system treated, such as the total quantity of cooling water or paper mill water.

The compositions may also be utilized for the preservation of slurries and emulsions containing carbohydrates, proteins, fats, oils, etc.; dosage levels for this purpose range in the vicinity of 0.01 to 5%. The com position of the invention which can be prepared by merely combining the respective ingredients and mixing thoroughly at standard conditions may be fed continuously to the treated system. e.g., by means ofu mctered pump, or may be fed periodically at predetermined intervals calculated to control the growth of slime-forming organisms in the system. Naturally, in

TABLE SC I Quantit of Percent kill Biocldal Material biocide (ppm) after 3 hours Compound A (5%), Compound B (5%), Inert (90%) 5 38 do. do. 'do. 84 do. do. do. 86 do. do. do. 50 92 do. do. do. 100 95 Pentachlorophenol (100%) 5 89 do. IO 94 do. 25 100 do. w 50 100 do. 100 100 Commercial Product active See Table 1C) 5 38 do. 10 36 do. 25 9 do. 50 0 do. 100 36 The composition of this Example exhibited overall desirable and attractive slime control capacity. Of special interest is the fact that a low percentage active concentrations the compositions were capable of controlling the slime-forming organisms.

When the inventive compositions are employed in the treatment of cooling or paper mill water, they are preferably utilized in the form of relatively dilute solutions or dispersions. For example, a preferred solution comprises between 5 to 65% by weight of the synergistic combination in admixture with various solvents and solubilizing agents. An example of such a synergistic biocidal product comprises from about 5 to 10% by weight of the phenol, from about 5 to 10% by weight of the 5-chloro-4-phenyl-l,2-dithiole-3-one and the remainder composed of such materials as surfactants, stabilizers, organic solvents, such as alkanols, aromatic hydrocarbons and/or water.

Surfactants such as the alkylaryl polyether alcohols, polyether alcohols, sulfonates and sulfates, and the like, may be employed to enhance the dispersibility and stability of these dispersions. The foregoing solutions of the biocidal compositions are utilized in order to insure the rapid and uniform dispersibility of the biocides within the industrial water which is treated. It has been found that either aqueous or non-aqueous solvents are generally suitable in the preparation of compositions of the invention, e.g., methyl cellosolve, organic solvents such as the aliphatic and aromatic hydrocarbons, e.g., kerosene. Based upon the synergism study as outlined above, it was ascertained that in the treatment of paper mill and cooling water effective biocidal action is obthe treatment of cooling water, the feeding of the inventive compositions must be designed to compensate for blowdown in those systems which employ that expedient.

to liquid formulations, the combinations of the inven tion may, of course, be formulated dry with well-known pelletizing agents, e.g., sodium chloride, talc, aluminate, etc, to produce solid pellets or briquettes which are added directly to the systems to be treated. The pellets or briquettes, of course, dissolve in accordance with predetermined conditions or rates.

In describing the inventive subject matter, the expression composition has been utilized. However, it is to be understood that physical compositions or combinations are not the sole utility of the invention. If, for example, the separate ingredients of the composition" are added independently to a particular system, it is intended that this usage of the subject matter is within the scope of the invention and is to be construed within the broad interpretation of composition and/or combination.

As would be expected, the inventive composition may be added to the cooling water or paper and pulp mill systems at any convenient point. Naturally, in once-through or non-circulating systems, the composition must be added upstream from the point of points at which microorganism control is desired. In circulating systems or pulp and paper systems, the compositions must be added at any point provided that the time lapse and the conditions experienced between point of addition and the point at which the effect of the com- Although the foregoing has been specifically directed position is to be experienced are not so drastic as to result in the neutralization of the effect of the composition.

Although the invention has been described specifically as being directed to specific compositions comprising 5-chlor0-4-phenyl-1,2-dithiole-3-one in combination with the phenol as described in Example 1, the phenylphenol of Example 2, the 2-chlorophenylphenol of Example 3, the chlorophenol of Example 4 or the pentylphenol of Example 5, it is obvious that homologues, analogues, etc., of the dithiole-3-one compound certainly are operable for the purpose. Likewise, the derivatives of the specially exemplified organobromine compounds also have utility in the present inventive concept. Moreover, as earlier described, mixtures of the various organo-bromine compounds would also serve the purpose. The provision, of course, is that the organo-bromine compound possesses biocidal or growth inhibitory capacity with respect to bacteria, fungi, and algae.

It should be noted that while the evidence has been derived from the treatment of samples taken from paper and pulp mill aqueous systems, the compositions and methods of the present invention are broadly applicable to the treatment of aesthetic waters as well as industrial waters such as cooling waters which are plagued by deposits formed by slime-forming organisms, or by the very presence of such organisms.

Having thus described the invention, what we claim 1. A method for controlling the growth of the microorganism Aerobacter aerogenes in an aqueous system in which said microorganism is found which comprises adding to said system so as to contact said microorganism an effective amount of a combination comprising 5-chloro-4-phenyl-l,2-dithiole-3-one and 2,3,4,6- tetrachlorophenol, wherein the weight ratio of the dithiole to the tetrachlorophenol is from 60 to 5% and 40 to 2. The method of claim 1 where said combination is added to said system in an amount of from 0.5 to about 1,000 parts by weight of said combination per million parts by weight of said aqueous system.

3. A composition which is effective in controlling the growth of the microorgamism Aerobacter aerogenes in aqueous system where said microorgansim is found which comprises 5-chloro-4-phenyl-l ,2-dithiole-3-one and 2,3,4,6-tetrachlorophenol wherein the weight ratio of the dithiole to the tetrachlorophenol is from 60 to 5% to 40 to 95%. 

1. A METHOD FOR CONTROLLING THE GROWTH OF THE MICROORGANISM AREOBACTER AEROGENES IN AN AQUEOUS STSTEM IN WHICH SAID MICROORGANIXM IS FOUND WHICH COMPRISES ADDING TO SAID SYSTEM SO AS TO CONTACT SAID MICROORGANISM AN EFFECTIVE AMOUNT OF A COMBINATION COMPRISING 5-CHLORO-4-PHENYL-1,2-DITHIOLE3-ONE AND 2,3,4,6-TETRACHLOROPHENOL, WHEREIN THE WEIGHT RATIO OF THE DITHIOLE TO THE TETRACHLOROPHENOL IS FROM 60 TO 5% AND 40 TO 95%.
 2. The method of claim 1 where said combination is added to said system in an amount of from 0.5 to about 1,000 parts by weight of said combination per million parts by weight of said aqueous system.
 3. A composition which is effective in controlling the growth of the microorgamism Aerobacter aerogenes in aqueous system where said microorgansim is found which comprises 5-chloro-4-phenyl-1, 2-dithiole-3-one and 2,3,4,6-tetrachlorophenol wherein the weight ratio of the dithiole to the tetrachlorophenol is from 60 to 5% to 40 to 95%. 